Hydraulic controls for bucket loaders



Aug. 18, 1970 J, FUZZELL '3 524,5.6Z

HYDRAULIC CONTROLS FOR BUCKET LOADERS Filed Sept. 19, 1968 2 sheets-sheet 1 INVEN TOR JOE E. FUZZELL BY Q ATTORNEYS Aug. 18, 1970 J. E. Fuzzsu. 3,524,562

HYDRAULIC'- CONTROLS FOR BUCKET LOADERS Filed Sept. 19, 1968 2 Sheets-Sheet z INVENTOR JOE E. FUZZELL WM, w, 6

ATTORNEYS United States Patent 3,524,562 HYDRAULIC CONTROLS FOR BUCKET LOADERS Joe E. Fuzzell, Peoria, Ill., assignor to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed Sept. 19, 1968, Ser. No. 760,886 Int. Cl. B66f 9/00 US. Cl. 214-762 4 Claims ABSTRACT OF THE DISCLOSURE A control circuit for actuating the bucket of a loader wherein the bucket is automatically stopped at certain positions by means which automatically release a detent which is holding the control valve at a given setting. The disclosure includes means to change the detent release position from the operators station. A time delay is also provided to prevent premature actuation of the release.

Frequently, loaders perform several different tasks during a days operation, and generally each task requires that the bucket be raised to a predetermined dump height. For efiicient operation, it is desirable that the bucket height be readjusted so that the bucket automatically stops at different predetermined dump heights. With the current arrangement, the kickout height is manually set by the operator by repositioning the kickout means. That adjustment operation is both time consuming and difficult, since the operator must climb down from his station to reach the kickout mechanism, especially on the larger machines now being developed. As a result, the kickout is generally set at the highest dump height required and the operator manually stops the bucket at the lower heights which causes more work for him to perform.

Also, it has been determined that during normal operation, it is deisrable for the bucket automatically to stop at two operational positions, namely the dump height and ground level dig position. To change the bucket from one position to the other, it is also desirable for the operator to be able to place the lift control lever in a detented position, and immediately remove his hand therefrom so that other operational functions can be performed. However, with the commercially available arrangements, the operator must momentarily hold the lever in the desired position until the trip mechanism moves away from the kickout means. This extra effort increases operator fatigue.

The invention will be more fully understood from the following specification wherein reference is made to the accompanying drawings.

In the drawings:

FIG. 1 is a view in side elevation of the forward part of a tractor and a loader mounted thereon;

FIG. 2 is an enlarged fragmentary view of the detent kickout mechanism of the present invention showing the parts in the dig position of the bucket;

FIG. 3 is a view similar to FIG. 2 illustrating the position of the parts as the upward travel of the bucket is interrupted;

FIG. 4 is a sectional view taken 'on the line IVIV of FIG. 3, and;

FIG. 5 is a diagram of the electrical circuit employed in the kickout control mechanism.

Referring now to FIG. 1, a tractor is shown as having laterally spaced lift arms, one of which is shown at 12, pivotally mounted at 14 with hydraulic jacks 16 adapted to raise and lower the lift arms in a conventional manner. A bucket 18 is pivotally mounted on the forward portions of the lift arms 12 and is adapted to be selectively tilted thereon by conventional tilt linkage 20 which includes a lever 22 pivotally mounted on a lift arm and to a link 24. As more clearly shown in FIG. 2,

3,524,562 Patented Aug. 18, 1970 "ice link 24 is pivotally mounted at its other end to the tractor frame by a stub shaft 26.

The trip mechanism generally shown at 28, functions to stop the bucket at two predetermined operational heights by causing the control valve (not shown) to return from a raise or float position to its neutral position, thus interrupting the flow to the jacks 16. The control valve and kickout cylinder are of the type described in my assignees patent to Rodney R. Erickson, number 3,289,546. The control valve has four positions being respectively, raise, wherein fluid is directed to the head end of jack 16 to effect raising of the lift arms, neutral, wherein the flow to and from both ends of the jacks is blocked, lower, wherein fluid is directed to the rod end of the jack 16 to effect lowering of the lift arms, and float, wherein communication is established between both ends of the jack 16 and the tank which permits the lift arms to be lowered by gravity. The control valve is held in the raise and float positions by a detent mechanism and the kickout cylinder functions to release the detent mechanism.

As shown in FIGS. 2 and 4, the trip mechanism 28 comprises a dry reed proximity switch 30, secured to a bracket 32 on the tractor frame and arranged to be actuated or closed by the influence of a ground level kickout magnet 34 or lift kickout magnet 36. As will be hereinafter described, closing the proximity switch 30 causes fluid to be directed to the kickout cylinder which releases the detent mechanism. The magnet 36 is attached to a clutch arrangement 38 contained within a clutch housing 39 and magnet 34 is attached to the clutch housing 39 which is supported by a bracket 40 secured to the link 24 so that the center axis of the clutch housing 39 coincides with the axis of pivot shaft 26. A bracket 41 with an arcuate slot and securing screws 42 enables adjustment of the position of the magnet 34. In the position shown in FIG. 2, the ground level kickout magnet 34 is in the position wherein the proximity switch is closed. Raising the lift arms causes rotation of the clutch housing 39 to the position shown in FIG. 3, wherein the lift kickout magnet 36 is in position to cause the proximity switch 30 to be closed.

The height at which the lift arms are stopped can be changed by adjusting the position of the lift kickout magnet 36 in relation to the clutch housing 39. As more clearly shown in FIG. 4, the adjustable means for changing the position of the lift kickout magnet 36, consists of the clutch arrangement 38 and a plunger type solenoid 44. The clutch arrangement consists of a cork ring 46 secured to a spring loaded plate 48 to which a shaft 50 is secured. The shaft 50 extends through a bearing 51 and supports a clutch arm 52 to which the lift kickout magnet 36 is secured. Activating the solenoid 44, which is done from the operators station, causes a plunger 54 to extend and engage a depression 56 in the clutch arm 52. With the plunger 54 so engaged, raising or lowering the lift arms causes rotation of the clutch housing 39 while the lift kickout magnet 36 is held fixed in relation to the proximity switch 30. The solenoid is then deactivated when the desired kickout height is reached.

The control means, as shown schematically in FIG. 5, comprises a power source 60 connected to a pressure switch 62 which is closed when the engine oil pressure exceeds 4 p.s.i. The purpose of switch 62 is to open the electric circuit when the engine is not operating, thereby preventing possible damage to the components and discharge of the battery. Closing the proximity switch 30 completes the electric circuit so that a current will be present in a coil 64 of a reed relay switch 66. The current in the coil 64 causes a magnetic field which closes the reed relay switch 66 and keeps it closed as long as the current is present. However, the duration of the current in the coil 64 is only momentary (approximately 1 /2 seconds) due to a capacitor 68 in the circuit between the relay switch and the ground connection. When the capacitor becomes fully charged, the flow through the coil is stopped. The 1 /2 seconds is a function of the resistance of the coil 64, the resistance of resistor 72, and capacitance of the capacitor 68. Closing the relay switch 66 completes a separate circuit to a solenoid control valve 70 which when activated, directs pressurized fluid to the kickout cylinder (not shown) to release the detent mech anism to allow the lift control valve to return to its neutral position. After the 1 /2 seconds time lapse, the relay switch opens, thus breaking that circuit and deactivating the solenoid control valve 70 so that the flow of fluid to the kickout cylinder is blocked. Thus, after the 1 /2 seconds time lapse, the control valve can again be put in one of the detented positions. As long as the switch 30 remains closed, the capacitor 68 will remain charged. However, when the switch 30 opens, the capacitor 68 will discharge through a resistor 72 in approximately 1%. seconds and the cycle can then be repeated.

The circuit for actuating the adjusting solenoid 44 is interconnected with the kickout circuit in that the silicon controlled rectifier 76 is triggered by the current from the proximity switch 30. The rectifier 76 is a rectifying device that normally blocks the current in both directions but can be triggered to allow current in the forward direction while still blocking in the reverse direction. When the proximity switch 30 is closed, current is applied to the gate of the rectifier 76 via the resistor 78, and if the manual switch 80 is closed, the circuit to the solenoid 44 will be completed, thus activating the solenoid. The function of the resistor 78 is to reduce the current to the gate of the rectifier. The function of a diode 81 is to prevent the capacitor '68 from discharging through the coil 64 as the switch 30 opens. Diodes 82 and 84 are employed as induced voltage suppressors to prevent excessive arcing of the contacts of switch 66 and damage to the rectifier 76.

A typical operation cycle of the tractor normally starts with the bucket in the ground level dig position shown in FIG. 1. The control valve is placed in the detented raised position and the lift arms start to raise. As the lift kickout magnet 36 approaches the proximity switch 30, the switch 30 closes, thus completing the circuit to the solenoid control valve 70 as previously described and the control valve returns to the neutral position, thus stopping the lift arms. To lower the bucket, the control valve is put in the detented float position and the lift arms start to lower, thereby causing the lift kickout magnet 36 to rotate away from the proximity switch 30, allowing the switch to open. Opening the switch 30 allows the capacitor to discharge so that by the time the ground level kickout magnet 34 approaches the switch, the kickout circuit is again ready to cause the control valve to return to the neutral position.

To raise the lift kickout point, the lift arms are raised to a position below the previous kickout height, and the manual switch is closed. Raising the lift arms is continued and as the lift kickout magnet 36 causes the proximity switch 30 to close, the solenoid 44 will be activated to extend the plunger 54 to engage the depression 56 in the clutch arm 52, thereby holding the lift kickout magnet 36 against movement relative to the proximity switch 30. When the desired bucket height is reached, the control valve is returned to neutral and the manual switch 80 is released. The new kickout point is now set.

To. lower the kickout height, the lift arms are raised until kickout occurs. The manual switch 80 is then closed, and the lift arms lowered to the desired kickout height and the manual switch 80 is then opened.

I What is claimed is:

1. In a tractor mounted loader of the kind having a bucket on power actuated lift arms controlled from the tractor operators station to initiate raising movement of the arms, and means acting in response to the position of the arms and height of the bucket relative to the ground to stop the raising movement, the improvement which comprises, means operable from the operators station to vary the position at which'the bucket is stopped, said last means including a part fixed to the tractor and a part moveable with the arm, means to effect adjustment of the latter part relative to the arm, said part moveable with the arm being frictionally held to the arm, and means operable from the operators station to engage and hold said part against movement while the arm is moved.

2. The improvement of claim 1 in which one part includes a proximity switch, and the other part includes an actuator therefore.

3. The improvement of claim 1 in which the means to engage and hold comprises, a depression in one part and an electromagnetically actuated detent on the other part which registers, upon actuation, with said depression.

4. In a tractor mounted loader of the kind having a bucket, power actuated means for raising and lowering the bucket, an operators station with controls for initiating raising and lowering of the bucket, means operable in response to bucket positions to effect disengagement of said controls, the improvement which comprises an electrical circuit which triggers such disengagement, and time delay means-in the circuit to prevent re-engagement of the controls until the bucket reaches a position intermediate its starting and stopping position.

References Cited UNITED STATES PATENTS 3,141,562 7/1964 McAdams 214-762 3,155,252 11/1964 Muellner et al. 214-762 3,204,794- 9/1965 Washbond 214-762 3,429,471 2/1969 Austin et a1. 214-762 3,435,974 4/ 1969 Omon 214762 H. O. SCHULZ, Primary Examiner 

